20 E. Greenly — Samhtone Pipes. 



Aire from tlie hills above Kildvvick and Cononle}'. I have given the 

 above-mentioned observations to prove that there is now going on 

 a steady transport of material, but the same conclusion is manifest 

 to the reason, for there are places on the mountains where the rock 

 is conspicuously bare, naked, and fresh-looking, being free from 

 asperities and from vegetable growth ; such spots, reason tells us, are 

 the places where there is a perpetual or oft repeated fall of stones 

 from above. There is such a nalced rock on Clogwyn y Garnedd, 

 under the summit of Snowdon ; and though I have not actually seen 

 stones falling there, I am as sure that the naked appearance of the 

 rock is due to falling stones as if I had seen them fall. Such bare 

 places on the mountain-sides are very conspicuous in some parts of 

 Norwaj' ; and the natives tell yo\i that they are due to 'stane scree.' 

 Anotlier sign that a rock is now wasting away is this : if the 

 ground beneath a cliff is thickly strewn with blocks of the same 

 rock as that of which the cliff is composed, you may be quite sure 

 that the cliff is now wasting away, A geologist must be careful 

 how he hammers such a cliff at its foot, for even a slight blow of 

 his hammer may bring down a mass of rock on to his head. Again, 

 the spiky character of a serrated ridge is proof that the ridge is 

 wasting away. Such wasting away is mainly due to frost ; and 

 I have noticed that in the Spring the mountain-sides are in a more 

 crumbly and unstable state than at any other time of the year. 

 This is doubtless due to the winter frosts. I have now said enough 

 to show that denudation is steadily going on, though its amount may 

 be small in comparison with the size of the hills. 



IV. — On Sandstone Pipes in the Carboniferous Limestone at 

 DwLBAN Point, East Anglesey. 



By Edward Greexly, F.G.S. 



THE low, but rocky headland of Dwlban Point forms the western 

 corner of Red Wharf Bay, on the east coast of Anglesey ; ^ and 

 is on the coastline of the principal tract of Carboniferous rocks in 

 the island, not very far from the boundary fault which runs out 

 to sea beneath the sands of the bay. The Carboniferous Limestone 

 near the Point is for the most part a light-grey, crystalline rock, 

 with abundant crinoids, corals, and other marine fossils. There are, 

 however, four beds of sandstone, varying from 2 to 9 feet thick, and 

 some of the Limestone itself also contains scattered grains of 

 quartz. The sandstones are clean white rocks, generally fine, but 

 with occasional thin seams of small pebbles. 



Now the foreshore at Dwlban Point is composed of a massive bed 

 of light-grey, crystalline Limestone. The surface of this bed, at 

 a little creek close to the headland, is pierced by a large number of 



' Abstracts of this and of the succeeding paper were read before the British 

 Association, Dover, 1899. 



* During tlie first examination and the mappin"- of this ground I was accompanied 

 by my friend Mr. J. R. Dakyns. I should like to add also that most of the 

 phenomena here described were noticed more than twenty years a"-o by Mr. G. H. 

 Morton, F.G.S. ° ^ 



